Major Topics Ch1-13(excluding Ch5&12)

Ch3: Molecular/Empirical Formula, Combustion Analysis, Limiting Factor

Ch4: Net Ionic Equations, Aqueous Stoichiometry

Ch6: Energy of a Photon, Quantum Numbers

Ch7: Explaining Trends from PT

Ch8: Lewis Structures/Formal Charge

Ch9: Molecular Shapes

Ch10: Gas Laws, Collection Over Water

Ch13: Freezing Point Depression, Boiling Point Elevation, Osmotic Pressure

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Practice Exercise 3.15 Determining Empirical Formula by Combustion Analysis

(a) Caproic acid, which is responsible for the foul odor of dirty socks, is composed of C, H,

and O atoms. Combustion of a 0.225-g sample of this compound produces 0.512 g CO2 and

0.209 g H2O. What is the empirical formula of caproic acid? (b) Caproic acid has a molar

mass of 116 g/mol. What is its molecular formula?

1st) Find moles of C & H.

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2nd)Find grams of C & H.

3rd)Find grams of O.

4th)Find moles of O.

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C3H6O

5th Find EF.

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6th Find MF.

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Practice Exercise 4.4 Writing a Net Ionic Equation

a) Write the net ionic equation for the precipitation reaction that occurs when solutions of

calcium chloride and sodium carbonate are mixed.

CaCl2 (aq) + Na2CO3 (aq) → CaCO3 (s) + 2NaCl (aq)

Ca2+ Cl– + Na+ CO32– → CaCO3 + Na+ Cl–

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Practice Exercise 6.3 Energy of a Photon

(a) A laser emits light with a frequency of 4.69 × 1014 s–1. What is the energy of one photon of the radiation from this laser? (b) If the laser emits a pulse of energy containing 5.0 × 1017 photons of this radiation, what is the total energy of that pulse? (c) If the laser emits 1.3 × 10–2 J of energy during a pulse, how many photons are emitted during the pulse?

E = h

=

6.626 10−34 Js x 4.69 × 1014 s–1 = 3.11 × 10–19 J

5.0 × 1017 photons x 3.11 × 10–19 J / photon = 0.16 J

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Sample Exercise 8.15 Lewis Structures and Formal Charges

The following are three possible Lewis structures for the

thiocyanate ion, NCS–:

(a) Draw the Lewis Structures (b) Which Lewis structure is

the preferred one?

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Solve (a) Neutral N, C, and S atoms have five, four, and six valence electrons, respectively. We can determine the following formal charges in the three structures by using the rules we just discussed:

As they must, the formal charges in all three structures sum to 1–, the overall charge of the ion. Middle preferred. Least amount of formal charge and –charge on most electronegative element(N)

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Practice Exercise 9.1 Using the VSEPR Model

4 e- domains EDG: tetrahedral

2 bonding domains, 2 nonbonding domains MG: bent

3 e- domains EDG: trigonal planar

3 bonding domains, 0 nonbonding MG: trigonal planar

Use the VSEPR model to predict the Molecular Geometry & draw (a) SeCl2, (b) CO32–, (c)

CH2O (d) ClO3– (e) CO

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3 e- domains EDG: trigonal planar

3 bonding domains, 0 nonbonding MG: trigonal planar

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2 lines & 1 “wedge”

4 e- domains EDG: tetrahedral

3 bonding domains & 1 nonbonding MG: trigonal pyramidal

(e) CO All 2 atom molecules have a linear MG.

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In the first step in the industrial process for making nitric acid, ammonia reacts with oxygen in the presence of a suitable catalyst to form nitric oxide and water vapor:

Practice Exercise 10.9a Relating the Volume of a Gas to the Amount of

Another Substance in a Reaction

4 NH3 (g) + 5 O2 (g) → 4 NO(g) + 6 H2O(g)

How many liters of NH3(g) at 850 °C and 5.00 atm are required to react with 1.00 mol of O2(g) in this reaction?

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4 NH3 (g) + 5 O2 (g) → 4 NO(g) + 6 H2O(g)

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Sample Exercise 13.13 Molar Mass from Osmotic Pressure

The osmotic pressure of an aqueous solution of a certain protein was measured to determine the protein’s molar mass. The solution contained 3.50 mg of protein dissolved in sufficient water to form 5.00 mL of solution. The osmotic pressure of the solution at 25 °C was found to be 1.54 torr. Treating the protein as a nonelectrolyte, calculate its molar mass.

5.00 ml = 5.00 × 10–3 L

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3.50 mg = 3.50 × 10–3 g